1. FIELD OF INVENTION
The present invention relates to means for achieving fluid tight seals between juxtaposed mechanical components under conditions of severe heat, high pressure and reactive chemical environments. In particular, the present invention pertains to high pressure, high temperature and chemically passive gas tight demountable seals between dissimilar materials.
Chemical incompatibility at elevated temperatures between juxtaposed but dissimilar material parts may be circumvented by mechanically isolating the incompatible parts with suitably selected gasket and sealing material. However, chemical incompatibility, as between the gasket seal material, on the one hand, and the contained fluid or gases, on the other hand, is a substantially more difficult problem to overcome. Earlier extreme condition sealing arrangements have not been altogether adequate for many applications. One specific severe condition application where the conventional seal apparatus proved inadequate, may be found in high temperature and high pressure sample containers for infrared spectrophotometer chemical analysis.
Accordingly, there is an existing need and requirement for a long life demountable secure fluid tight seal for juxtaposed mechanical parts suitable for high temperature, high pressure and chemically reactive environments. Moreover, it is further required that such seal be fully effective when the juxtaposed parts are made of dissimilar materials, and that the seal apparatus does not excessively stress the juxtaposed parts mechanically thermally or in any other respects.
2. DESCRIPTION OF PRIOR ART
Interfaces of dissimilar materials, such as metal and non-metal parts when a fluid or gas tight seal is desired, is readily achieved between chemically compatible materials at ambient temperatures and pressures. An elastomer "0" ring washer or shaped elastomer gasket seal compressed between matched interfaces of two dissimilar material parts will normally provide a gas tight seal. However, as chemical incompatibility, higher temperature and higher pressure factors are introduced, the aforesaid conventional elastomer sealing means becomes less secure and less dependable during extending service.
While numerous novel and generally effective sealing means have been devised to secure under extreme conditions of temperature and pressure fluid tight seals between juxtaposed parts made of dissimilar materials, these earlier extreme condition sealing means resulted in substantial thermal isolation of the juxtaposed parts. As a result, with conventional sealing means, gas tight sealing may be achieved but sharp thermal gradients and excessive mechanical strain, on one or both of the juxtaposed parts, is likely to be encountered. When one of the juxtaposed parts is transparent to radiant energy, as in the visible or infrared spectrum, the presence of severe thermal gradients distorts and alters adversely the radiation transmission properties of the transparent material. Crystalline and non-metal material parts during pressure and temperature cycle extremes are often fragile. Excessive mechanical and thermal stresses will often cause breakage.